1. Field of the Invention
This invention relates to an automatic focusing apparatus for a video camera, and more particularly to an automatic focusing apparatus for a video camera using a solid state image pickup device.
2. Description of the Prior Art
In conventional video cameras, focusing is automatically effected by activating a helicoid drive motor with a position signal fed from a distance measuring device, which measures the distance from the object, thereby controlling the movement of the camera lens. Further, in a video camera using a solid state image pickup device, it has been proposed in Japanese Unexamined Patent Publication No. 55(1980)-149575 to automatically focus the camera by moving the solid state image pickup device instead of the camera lens according to a position signal fed from a distance measuring device of the type described above, thereby simplifying the automatic focusing apparatus.
However, the conventional automatic focusing apparatuses described above require complicated constructions and are expensive because it is necessary to use a distance measuring device, for example one using an ultrasonic wave, for measuring the distance from the object.